Evaluation Strategy. Since there are no 3D ground truths available for CUB, we evaluate MeshInversion against various baselines from three aspects: 1) We evaluate the geometry accuracy in the 2D domain by IoU between the rendered masks and the ground truths.
2) We evaluate the appearance quality by the image synthesis metric FID [1]}, which compares the distribution of test set images and the render of reconstruction.
Since a plausible 3D shape should look photo-realistic observed from multiple viewpoints, we report both single-view FID (FID\(_{1}\)) and multi-view FIDs. Following SMR [2]} and View-gen [3]}, we render our reconstructed 3D shape from 12 different views (FID\(_{12}\)), which covers azimuth from 0\(^{\circ }\)  to 360\(^{\circ }\)  at an interval of 30\(^{\circ }\) . We additionally report FID\(_{10}\) since the exact front view (90\(^{\circ }\) ) and the exact back view (270\(^{\circ }\) ) are rarely seen in CUB. Note that this is in favour of existing methods that do not use any GAN prior as ours.
3) Apart from extensive qualitative results, we conduct a user study to evaluate human preferences in terms of both shape and appearance.
For PASCAL3D+, it provides approximated 3D shapes using a set of 10 CAD models, which allows us to evaluate geometric performance in terms of 3D IoU.
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